1. Field of the Invention
The multi-functional hand strength assessment device permits quantification of three aspects of hand strength: grip hand strength, finger pinch strength, and twisting hand strength.
2. Description of Related Art
This disclosure is directed to the field of medical apparatus used to measure the grip strength of a person's hand, the pinch strength between two digits of the hand, and twisting or torque strength of a person's hand. It is useful for doctors to be able to objectively monitor the progress of patients who have suffered hand injury, either through accidents or debilitating diseases, such as arthritis, or who have undergone hand surgery.
Numerous devices are known in the medical field for measuring aspects of human hand strength. U.S. Pat. No. 2,708,367 to Lusk discloses a force dynamometer adapted to measure hand strength. The Lusk hand grip measurement device utilizes a force gauge that measures the applied force remotely from the point of application by means of hydraulic pressure transmitted through a liquid filled connection of pre-set length. U.S. Pat. No. 3,672,219 to Van Patten discloses a handgrip dynamometer equipped with an electric transducer which is connected to a volt meter. U.S. Pat. No. 4,674,330 to Ellis discloses an apparatus for measurement of both the grip strength of a person's hand and pinch strength of two digits of the hand. The Ellis apparatus comprises two parallel grip handles extending at right angles from a third member. A handle is rigidly fixed to the third member and has two pairs of strain gauges mounted thereon to measure the force applied to the handles irrespective of where that force is applied. The grip handles are adjustable with respect to the strain gauge handle to alter the distance between the grip handles which terminate in flat portions to be used for measurement of pinch strength.
A traditional device used to assess grip strength in the clinical setting as well as in experimental investigation is the Jamar® dynamometer. U.S. Pat. No. 4,884,445 to Sadoff et al. discloses an otherwise conventional Jamar® dynamometer that is provided with a force transducer. The analog output of the force transducer is sampled at regular intervals and converted to a sequence of digital values by a conventional analog-to-digital converter. The digital output of the converter is processed by a conventional computer in real time to produce an output that clearly indicates the maximum force exerted by the test subject. The output may be both a graphic display of the forces exerted by the test subject over a predetermined interval of time and a statistical analysis of those forces.
U.S. Pat. No. 4,949,729 to Hash discloses a hand grip assessment apparatus that comprises a fluid filled compressible object, such as an inflatable bladder, and a pressure transducer in fluid communication with the inflatable bladder. The pressure transducer is connected to a circuit used to determine the rate of change with time of the logarithm of the pressure of the fluid in the inflatable bladder between predetermined lower and upper pressure levels. This information is displayed and/or recorded for hand grip assessment purposes.
U.S. Pat. No. 5,125,270 to Kovacevic discloses a human hand load sensor that uses a strain gauge force measurement instrument which has two platforms or handles that can be moved together with parts of the human hand, for example, a thumb and finger, or the handles can be grasped between the heel of the hand and several fingers. The instrument permits measuring of strength force by supporting a movable handle relative to a base or reference handle through a flexure system which deforms predictably under shear loading as the handles or platforms are moved together.
U.S. Pat. No. 5,157,970 to Lewis, Jr. discloses a hand grasp analysis apparatus and method by which the power of grasp exerted by the human hand can be measured. The apparatus includes a housing having opposed walls which can be forced towards one another in proportion to the magnitude of the compressive strength exerted by the person that grasps the housing. A transducer enclosed within the housing is compressed between the movable opposed walls and provides a signal that is proportional to the magnitude of the compressive force of the grasp. The signal is converted into a measurement indicative of the magnitude of the force.
U.S. Pat. No. 5,170,663 to Kovacevic discloses a grip sensor that is formed from a unitary block having upper and lower covers. The grip sensor comprises two sets of parallel flexure beams connected between outer end blocks and a center block and are loaded by a base plate connected to the outer end block and extending between the end blocks. The flexure beams deflect to respond to hand grip strength. Strain sensors located on the flexure beams and connected in a wheatstone bridge provide indication of gripping strength.
U.S. Pat. No. 5,299,457 to Pang et al. discloses a grip meter that includes a frame, a base on the frame sized and shaped to engage the palm of the hand, a plurality of plungers on the frame opposite the base and located for being depressed by corresponding fingers of the hand, and a device associated with the base and the plungers for simultaneously measuring and recording both finger strength and overall hand strength. The disclosed grip meter is symmetrical so that it can be used for measuring the finger and hand strength of either the left hand or the right hand.
U.S. Pat. No. 5,317,916 to Kovacevic discloses a digit grip sensor for measuring the grip strength of the human hand. The digit grip sensor comprises a post support having a first and a second sensor therein. A first post extends through the first sensor and a second post extends through the second sensor. A crossbar spaced from the post support extends between the first post and the second post. Each sensor has a plurality of strain gauges mounted thereon for measuring the deflection of the sensor. The crossbar can have a plurality of individual digit sensors mounted thereon for measuring the contributions of each finger to the grip force. The crossbar and the individual digit sensors can be adjusted for various hand and finger sizes.
U.S. Pat. No. 7,152,471 to Baratz et al. lists as an inventor the inventor of the subject disclosure. This patent discloses an apparatus and method for determining the strength of the hand based on a twisting action with the hand.
U.S. Pat. No. 7,467,551 to Yang discloses a grip strength detection device which includes a handle for the user to hold and apply a force, the movement of which drives a cable which rotates a shaft. A disk is connected to an end of the shaft and includes protrusions which pass through a photoelectric sensor so as to detect the angular distance that the disk travels. The angular distance is transferred into the value of the grip strength.
U.S. Pat. No. 7,470,217 to Jones-Glaser discloses a grip strength device that is configured to gauge the grip strength of contracted muscles or aid in exercising particular muscles by providing resistance against the contracted muscles. The grip strength device has a removable casing containing a first fluid, a first bellows, a second bellows, and a pressure gauge. The first bellows has a closed end and a first valve in communication with the casing. The second bellows has a second fluid. The second bellows has a second valve connected to the pressure gauge and a closed end abutting the closed end of the first bellows. Pressure applied to the removable casing is communicated from the first bellows to the second bellows and measured by the pressure gauge.